To use the favicons insert into your head section some of these tags accordly to your needs.

    <!-- For old IEs -->
    <link rel="shortcut icon" href="favicon.ico" />

    <!-- For new browsers - multisize ico  -->
    <link rel="icon" type="image/x-icon" sizes="16x16 32x32" href="favicon.ico">

    <!-- For iPad with high-resolution Retina display running iOS ≥ 7: -->
    <link rel="apple-touch-icon-precomposed" sizes="152x152" href="favicon-152.png">

    <!-- For iPad with high-resolution Retina display running iOS ≤ 6: -->
    <link rel="apple-touch-icon-precomposed" sizes="144x144" href="favicon-144.png">

    <!-- For iPhone with high-resolution Retina display running iOS ≥ 7: -->
    <link rel="apple-touch-icon-precomposed" sizes="120x120" href="favicon-120.png">

    <!-- For iPhone with high-resolution Retina display running iOS ≤ 6: -->
    <link rel="apple-touch-icon-precomposed" sizes="114x114" href="favicon-114.png">

    <!-- For iPhone 6+ -->
    <link rel="apple-touch-icon-precomposed" sizes="180x180" href="favicon-180.png">

    <!-- For first- and second-generation iPad: -->
    <link rel="apple-touch-icon-precomposed" sizes="72x72" href="favicon-72.png">

    <!-- For non-Retina iPhone, iPod Touch, and Android 2.1+ devices: -->
    <link rel="apple-touch-icon-precomposed" href="favicon-57.png">

    <!-- For Old Chrome -->
    <link rel="icon" href="favicon-32.png" sizes="32x32">

    <!-- For IE10 Metro -->
    <meta name="msapplication-TileColor" content="#FFFFFF">
    <meta name="msapplication-TileImage" content="favicon-144.png">
    <meta name="theme-color" content="#ffffff">

    <!-- Chrome for Android -->
    <link rel="manifest" href="manifest.json">
    <link rel="icon" sizes="192x192" href="favicon-192.png">

For more informations about favicons consult The Favicon Cheat Sheet by Audrey Roy.